On Expansion of Magnetic Clouds in the Solar Wind

Magnetic clouds are supposed to be large inter- planetary flux ropes propagating away from the Sun. Due to enhanced inner magnetic pressure, they expand during their travel. We have analyzed 21 magnetic clouds from Wind ob- servations and fitted them by our model. Comparison of the time-dependent model with observations is shown for sev- eral cases with a detailed discussion. The model describes behavior of compared quantities satisfactorily. In addition to magnetic field vectors, also velocity vectors were modeled and it was found that radial velocity component behaves as expected. Analysis of velocity components put models under a more strict test and yields more confidence into models and derived magnetic cloud parameters. and yields a fairly good agreement between modeled and ob- served profiles of magnetic field components.